JPS58198173A - Piezoelectric rotating device - Google Patents

Abstract

PURPOSE:To remove unpleasant audible sound when a piezoelectric bendable vibrator is driven by applying an AC signal of harmonic range through a retainer terminal having an elasticity to the piezoelectric bendable vibrator. CONSTITUTION:When an AC signal of the range which is not heard by human ears is applied by a drive circuit, a piezoelectric bendable vibrator 13 fluctuates. A terminal 15 which has an elasticity is bent rightwardly as shown by an arrow due to the displacement by the fluctuation, and repelling force which tends to return the fluctuation to the original position is applied to the vibrator 13 as a force 20 at the next moment. This force 20 is operated obliquely upwardly, and the gravity G' of the vibrator 13 is accordingly displaced vertically. Rotary force 21 is produced by the displacement of the gravity g', and the vibrator 13 rotates. Accordingly, since the input to the vibrator is a signal of harmonic range, unpleasant audible sound is not generated when the vibrator is driven.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a piezoelectric rotating device that utilizes bending vibration of a piezoelectric bending vibrator.

#c1 Figure (a) 1 as a component of a conventional one-rotation device
b) 1 As shown in the figure, a stator made of a permanent magnet 1 made of barium ferrite, samarium cobalt, etc. has an electromagnet 4 in which a coil 3 is wound around a ferromagnetic material 2 such as iron or sendust as a rotor. , one in which more rotational torque is given to the rotor due to the interaction 1υ of the alternating current magnetic field caused by the alternating current flowing through the coil 3 through the brush 5 and the magnetic field caused by the permanent magnet l, or the one shown in FIG.
As shown in the figure, a permanent magnet 6 made of barium ferrite, samarium cobalt, etc. is used as a rotor, and around this, an electromagnet 9 with a coil 8 wound around a ferromagnetic material 7 such as wire or sendust is arranged. There are mainly those that use magnetic means, such as those that apply rotational torque to the rotor through the interaction between the alternating current magnetic field generated by the flowing alternating current and the magnetic field created by the permanent magnet 6, which is one rotor. ing.

These include well-known motors, brushless motors, and the like.

However, devices using such magnetic means have the disadvantage that it is difficult to achieve noiseless and low rotation speeds. In other words, in a general motor, the rotor tends to generate noise when rotating, and if the rotation speed without a gear is about 1100 rpm, then in order to reduce this rotation speed to about 100 rpm, for example, it is necessary to use a motor that is inversely proportional to the rotation speed ratio. It is possible to use a gear having a tooth ratio, but if this is done, the torque will increase accordingly.

By the way, for example, when a pyroelectric infrared detector or a thermistor bolometer is used as an infrared radiation thermometer, a rotating device with a low rotation speed and low torque is used as a mechanism.゛Because these thermal infrared detectors have a large time constant, they have maximum sensitivity at the low rotational speed of the chiso tube (0.5~IQ) (z), and Since there is no load on the device just by tipping, a large torque is required.In fact, since this type of radiation thermometer is often portable, excessive torque will result in consumption (a large loss of power).

This is because both the ** type and thermistor type have high impedance, and the infrared detection signal control circuit uses several mW to several I
This is because only QmW of extremely small power is consumed.

Therefore, as mentioned above, 1
11 with a magnetic means motor that rotates steadily at 1000 rpm.
01) Use an Orp gear to reduce the rotation speed 7. At this time, the torque is 10 times greater, and all the energy equivalent to this torque - hg is lost, and if a dry battery is used as a power source, its consumption will be extremely rapid. Shimari. Therefore,
If the input current to the motor is suppressed to suppress this increase in torque, the gear load 6 motor will become unable to start.

In this way, the use of a motor slowed down by a gear as a power source for an infrared radiation thermometer using the IIE #1 infrared detector or thermistor bolometer has the disadvantage of being extremely uneconomical in terms of energy conservation. There was □.

In addition, since the above-mentioned magnetic means utilizes magnetic action, it attracts ferromagnetic dust such as iron powder, especially if it gets into the rotating contact area where the number of parts is large and the 4I structure is complex. Not only will the rotor rotate unevenly, but the electrical contact will also become unstable, producing noise.If the machine is operated in this condition for a long time, the rotor may become unable to rotate due to rapid wear of the rotating contact parts. be. This type of accident can occur when an infrared radiation thermometer is used to measure the temperature inside a roasting furnace at a steel plant without contact, or to measure the heating status caused by friction in a bearing. It has the drawback of lacking stability, which occurs frequently when observing in a vacuum.

Furthermore, it was difficult to reduce the thickness of the device using the above-mentioned magnetic means. In other words, in a conventional motor, the rotational moment of the rotor is proportional to the area of the part where the magnetic flux produced by the stator-side permanent magnet and the alternating current magnetic flux produced by the rotor are electrically conductive. As the area is reduced, the rotational moment of the rotor becomes smaller accordingly. Therefore, for example, if such a motor is
When used as a collar, the overall thickness is limited by the axial length of the motor, even though the chip itself can be very thin, making it difficult to make it thinner as a rotating device. there were.

This invention was made to eliminate the above-mentioned drawbacks, and it utilizes the bending vibration of a piezoelectric bending vibrator, eliminates unpleasant audible sounds when the vibrator is driven, and also achieves low rotation and low power consumption. It is an object of the present invention to provide a piezoelectric type rotating device that can also be made into a shape.

An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 3 1a) ibl, 11 is a piezoelectric element having electrodes (r not shown) on both sides, and this piezoelectric element 11 is connected to the metal plate 1.
The piezoelectric bending vibrator 13 is provided on the plate surface of the second plate. In this case, specifically, the piezoelectric element 11 is made of piezoelectric ceramic such as PZT or lead titanate.
After applying a gold film of Ag, Ni, Cu, etc. as i, by means such as vacuum evaporation, sputtering, terminating, or baking, 1!
This is obtained by polarization treatment in the direction of brass.

Metal plate 1 made of SUs, IJ steel, titanium, etc.
2 using an adhesive made of epoxy resin, acrylic resin, cyano tree, or resin in which metal powder is dispersed in these resins to form a disc-shaped piezoelectric bending vibrator 13. .

Such a vibrator 13 is held at the tips of a pair of holding terminals 15 and 15 implanted in the base 14.

This holding terminal 15.15 is made of a spring conductive material such as phosphorus steel or steel, and the tip portion that holds the vibrator 13 is
It is bent so that the angle with the plane of is kept at an acute angle φ. Here, φ should not exceed 90'.

A drive circuit 17 is connected to the holding terminal 15.15 via a lead wire 16.16. This drive circuit 17 includes an IC circuit 171 consisting of six inverters as shown in FIG.
, a resistor 172 . that determines the oscillation frequency. capacitor 17
3. Protective resistance 174. Power supply terminal 175 of IC circuit 171
It has a ground terminal 176 and a ground terminal 176, and is designed to generate an alternating current voltage of a predetermined frequency and about twice the voltage applied to the power supply terminal 175. In this case, if such specified frequency and voltage are obtained, the illustrated four elements 131 of the camera element 13 may be grounded.

By the way, it is known that the L-K piezoelectric bending vibrator 13 has a unique resonant frequency (II'r) due to its size, material, and the point in which it is held, as shown in the following equation.

1tlj, t is the thickness, a is the diameter, and σ is Poisson's ratio.

E is Young's modulus, ρ is density, and α is a constant.

As an example, if we consider a vibrator in which PZT with a diameter of 13 m/mφ and a thickness of 0.25 m/m is glued to an 8US plate with a diameter of 18 m/mφ and a thickness of 0.25 m/m, the nodes of this (a position l1m/mφ from the center) is about 10.5KJ (z, and when the center is held 7.
A resonance frequency a of about 0 KHz appears. Figure 5 shows this situation.

In the drawings, 1al shows the case where the node is held, and 1b) shows the case where the center is held. In this case, what should be noted in the drawing is the resonance frequency of 10.5 KHz and 7.0 KHz (7.0 KHz).
) There are so-called high 1-wave dust eyebrow points of odd-numbered orders, such as the 3rd order, 5th order, etc., and sound waves each having a large 1st wave are generated.

Therefore, in the present invention, we focus on such harmonic resonance points, and in particular, in the region inaudible to the human ear, that is, in the case of the above-mentioned one, the resonance frequency of the third harmonic is 21KH.
An AC signal having a frequency substantially equal to z is input from the drive circuit 17 to the vibrator 13. In this case, the voltage of the AC signal is tsvppm&.

Now, if the center of gravity of the vibrator 13 and the holding point of the holding terminal 15 are made to coincide with each other, and the above-mentioned AC signal is applied from the drive circuit 17 in this condition, the vibrator 13 will bend as shown by the broken line in the figure. do. here.

A diagram of the bent cap at a certain moment is shown in FIG. 6 1al. That is, when it is bent as shown in the figure C.

The vibrator 13 pushes the air on the left side in the figure, and the terminal 15 is displaced to the right as a reaction.

Due to this displacement, the springy terminal 15 is bent to the right as shown by the arrow in the figure, but at the next moment, a repulsive force acts on the vibrator 13 as a force 20 to return the spring to its original state. This force 20 acts in the diagonal L direction as long as the contact angle φ of the terminal 15 with respect to the sensor 13 is an acute angle. therefore.

A vertical component 201 of this force 20 causes the center of gravity 0' of the vibrator 13 to be displaced in the vertical direction against gravity. This state is shown at 13' in Figure 6 (b), and the center of gravity G' is located above the holding point G of the terminal 15.

Also, in this way, the center of gravity G' is F from the holding point G of the terminal 15.
If it goes to the side, it will become unstable, so I! A rotational force 21 as shown in Fig. 6 (cl) is generated, and the α point is moved to a place lower than the 0 point, resulting in the state shown in Fig. 6 (d). Also, from this plexus, the same force as the above-mentioned force 20 is generated. When the force 20' is applied, the operation shown in FIG. 6 1b) (a and d) is reversed again, and the camera element 13 rotates.

6) L, and according to this configuration, 1EllI
The i-curve vibrator is held at the tip of a holding terminal having spring properties.

By applying an alternating current signal in the harmonic range to the vibrator through this holding terminal, the vibrator is caused to bend and rotate. therefore,
Since the input to the camera element is a signal in the harmonic range, no unpleasant audible sound is generated when the vibrator is driven, resulting in a silent rotating device that is completely inaudible to the human ear. Further, the rotation speed of the vibrator is determined by the diameter and resonance frequency of the vibrator. Therefore, if the motor is driven at a frequency in the harmonic range as described above, the rotational speed will increase if the same applied voltage is applied, but the rotational speed can be lowered by reducing the applied voltage.

Incidentally, the rotation speed of the camera element is approximately several Hz.

Furthermore, reducing the applied voltage can suppress the increase in the power consumption due to driving by harmonic signals, and operation with low power consumption of several tens of milliwatts or less can be obtained.

This combination allows the vibrator to operate at low rotation speeds and with low dissipated power, resulting in significant energy savings compared to conventional gear-based magnetic means. Perfect as an adventure. In addition, it is thin and lightweight, and the configuration can be simplified.
It is not only easy but also economically advantageous. Furthermore, compared to conventional magnetic means, it is easy to suck in ferromagnetic dust, so stable operation can be expected at all times without instability of operation.

It should be noted that the present invention is not limited to the above-mentioned embodiments, but can be implemented with appropriate modifications within the scope of the invention.

For example, the piezoelectric bending vibrator 13 may be one in which two elements 11 are stacked and bonded so that their polarization directions are opposite to each other, as shown in Figure 7. In this way, the maximum displacement during bending can be made approximately twice as large as in the actual example described above.

Even in this case, the same effect as described above can be obtained. Further, the drive circuit 17 may use a transistor, a multivibrator, etc. as long as it generates a predetermined frequency and voltage.

As described above, according to the present invention, it is possible to provide a piezoelectric rotating device that can eliminate unpleasant noises when driving a vibrator, and also achieve low rotation and low power consumption, and can also be made thinner. .

[Brief explanation of the drawing]

@ t Ig (,1) lb) and Fig. 2 (a) lb) are schematic configuration diagrams showing conventional rotating devices, respectively, and Fig. 93 (a) 1
b) shows an example of actual ownership of this invention; C1 is the front; rb)
4 is a circuit diagram showing the drive circuit used in the same embodiment, FIG. 5 is a characteristic diagram for explaining the same embodiment, and FIG. 6 1a) (bl lc
1 ldl is an explanatory diagram for explaining the same embodiment, and FIG. 7 is a schematic configuration 1 showing an alternative legend of this invention. 1.6...Permanent magnet 2.7...Ferromagnetic material 3.
8...Coil 4,9...Electromagnet 5...Brush 11...Pressure 1 element 12...Metal plate 13...
・Compression bending camera element 14...Base 15...Holding terminal 16...Lead wire 17...Drive circuit
171...IC circuit 172...Variable resistor 1
73...Protective resistor 174...Capacitor Fig. 1 Fig. 4 Fig. 5 Person C No. 7 □4σ 16 to 14

Claims (1)

[Claims] (Claim) A piezoelectric bending transducer, a spring conductive material that holds the transducer so that the angle between the transducer and the vibrating surface is acute, and an eyelid that provides an alternating current signal at a frequency in the ultrasonic range. A piezoelectric rotating device characterized by comprising four circuits. (2) The piezoelectric rotating device according to claim 1, wherein the piezoelectric bending vibrator is a piezoelectric element bonded to a metal plate surface. (3) The piezoelectric bending vibrator is made up of two pieces of pressure (one gram) glued together with one glue so that the polarization directions are opposite to each other. 14) The piezoelectric rotating device according to claim 1 or h42, wherein the piezoelectric bending vibrator has a disk shape.